上颌中切牙阻生对颅面结构的影响及其矫治

目的：研究上颌中切牙埋伏阻生对颅面结构的影响并探讨其矫治方法。方法63例上颌中切牙埋伏阻生的病例,按照其牙列发育情况分为混合牙列组(32例)和恒牙列组(31例)。描记所有患者的头颅侧位片,测量15项角度和6项线距,将其测量值与对应的正常牙合对照组进行比较。结果上颌切牙埋伏病例的发病因素中,多生牙、含牙囊肿或牙瘤、外伤和不明原因各占6.3%、6.3%、12.4%和73%。头影测量显示上颌中切牙阻生病例SNA和ANB角较对照组显著减小(P<0.05),并伴有牙性变化即上颌切牙唇倾、下颌切牙舌倾(P<0.05)。在牙根发育早期( Nolla法第7期和第8期),13颗埋伏切牙中12颗正畸牵引成功；在牙根发育晚期(第9期和第10期),15颗埋伏切牙中7颗牵引成功。结论上颌中切牙埋伏阻生后,上颌发育受限；早期矫治可以提高埋伏牙成功率,同时有利于牙根发育。

Influence of impacted maxillary central incisor on craniofacial structure and its orthodontic treatment

Objective To explore the influence of impacted maxillary central incisor on craniofacial structure and its orthodontic treatment. Methods A total of 63 subjects with impacted upper central incisors were selected and catego-rized into the mixed ( n=32) and permanent dentition group ( n=31) . By using the lateral cephalograms of each subject, 15 angular and 6 linear measurements were made. The cephalometric data were analyzed and compared to data of its cor-responding control group with normal occlusion. Results Among the etiological factors of all 63 cases with impacted up-per incisors, supernumerary teeth, dentigerous cyst or odontoma, mechanical trauma and idiopathic factors comprise of 6. 3%, 6. 3%, 12. 4% and 73% respectively. Cephalometric analysis demonstrated a more retruded position of"A" point with decreased SNA and ANB angle in incisor impaction group. Dental compensations followed the decreased ANB angle with more proclined upper incisor and more upright lower incisor. In early stage of root development ( stage 7 and 8 of Nolla's method) , 12 out of 13 incisors were tracted successfully, whereas in late stage( stage 9 and 10) , 7 out of 15 inci-sors were extracted. Conlusions Upper central incisor impaction adversely influences maxillary development. Early or-thodontic treatment can improve successful rate and gain a better root morphology.